Question

Q.Using identities find the product -

a) (xyz - 4 ) ( xyz - 2)

b) (1.1m - 0.4 ) (1.1 m + 0.4

Answer 1

1. (xyz – 4)(xyz – 2)

Using the identity, (x + a)(x + b) = x² +(a + b)x + ab

∴ (xyz – 4)(xyz – 2) = (xyz)² + [(-4 )+ (-2)]xyz + (-4)(-2)

= x²y²z² – 6xyz + 8

2. (1.1m – 0.4 ) (1.1m + 0.4)

Using the identity, (x – a)(x + a) = x² – a²

∴ (1.1m – 0.4 ) (1.1m + 0.4) = (1.1m)² – (0.4)²

= 1.21m² – 0.16